Active traders and more active investors looking for news lists of stocks to buy or other investing ideas often look at stocks which are very active in trading volume. Some are up big, some are down big. Either way, large spurts of trading volume often lasts for multiple days. These are the major volume spikes tracked by 24/7 Wall St. this Monday.

Charter Communications, Inc. (NASDAQ: CHTR) just had a very unusual volume spike as shares were halted on an intraday circuit breaker. Dow Jones reported that Liberty’s John Malone is close to buying a 25% stake in the company. Stay tuned as shares are up 9% at $98.20 on 1.4 million shares versus almost 1 million shares on an average day.

Glu Mobile, Inc. (NASDAQ: GLUU) was raised to Outperform at Northland Capital and that was somehow enough to send shares through the roof with a 9% gain to $3.64. What was impressive was that the rise was on over 18 million shares in mid-day trading versus about 2.5 million shares. Perhaps that new $4.50 target implying 35% upside from the $3.34 close had something to do with it.

Incyte Corporation (NASDAQ: INCY) is approaching a 300% volume spike on news that one of its patients under treatment developed the brain infection PML. Shares are down 6.6% at $23.20 on over 6 million shares versus an average daily volume of 1.63 million shares.

Juniper Networks, Inc. (NYSE: JNPR) will not look like a huge unusual volume spike with 7.2 million shares having traded against a 6 million average daily volume. The problem is that the share volume on the sell-side was so large at the market open that shares opened down about 5% at $19.08. The stock is now down only 1% at $19.97 on the day.

Pacira Pharmaceuticals, Inc. (NASDAQ: PCRX) is down over 7% at $27.78 after it was pointed out that insiders were selling shares. What stands out is volume at 300% of normal at about 1.4 million versus average volume of 413,000 shares per day.

U.S. Silica Holdings, Inc. (NYSE: SLCA) remains above normal in trading volume as an institutional investor was shown to be selling shares last week. The stock is actually up 3% at $22.36 so far on Monday and the 2+ million shares compares to average volume of 744,000 shares.

ValueClick, Inc. (NASDAQ: VCLK) somehow did not even make our top analyst upgrades and downgrades this morning, but Jefferies raised the rating to Buy from Hold and raised the target price by $12 to $35 and sent the stock up. This was a gain of 9.5% mid-day to $30.40, and the share count of 1.8 million compares to an average volume of only about 955,000 shares per day.